Abstract: According to an aspect, a method comprises maintaining, by a cache control unit in a first packet data network, white and black lists of data servers in a second packet data network that are allowed or unable to use a cache server in the first packet data network, respectively; monitoring data traffic to and from data servers in the second packet data network over an interface between the first and second packet data network; comparing the candidate data servers to the data servers in the white and black lists; and in response to a candidate data server being in neither list, performing the following: causing sending a cache request to the candidate data server and in response to receiving an acknowledgement to the cache request within a pre-defined time, adding the candidate data server to the white list, otherwise adding the candidate data server to the black list.

Abstract: According to an aspect, a method comprises maintaining, by a cache control unit in a first packet data network, white and black lists of data servers in a second packet data network that are allowed or unable to use a cache server in the first packet data network, respectively; monitoring data traffic to and from data servers in the second packet data network over an interface between the first and second packet data network; comparing the candidate data servers to the data servers in the white and black lists; and in response to a candidate data server being in neither list, performing the following: causing sending a cache request to the candidate data server and in response to receiving an acknowledgement to the cache request within a pre-defined time, adding the candidate data server to the white list, otherwise adding the candidate data server to the black list.

Abstract: A cylinder liner with a plurality of protrusions on its outside surface and the manufacturing method thereof are disclosed. The protrusions are ?-shaped, P-shaped or taper-shaped, and the ?-shaped, P-shaped and taper-shaped protrusions are accounted for 50-99.5%, 0.5-30% and 0-20% of the total number of protrusions, respectively. The density of the protrusions on the outside surface of the cylinder liner is 15-65 per square centimeter. The outer surface of the protrusions of the cylinder liner is curved, and has a large contact area and a concave which can be filled by an aluminum sheath to improve the radial bearing capacity, so as to effectively improve the bite force between the cylinder liner and the outside aluminum sheath and prevent the cylinder liner from breaking away from the cylinder body.

Abstract: A cylinder liner with a plurality of protrusions on its outside surface and the manufacturing method thereof are disclosed. The protrusions are ?-shaped, P-shaped or taper-shaped, and the ?-shaped, P-shaped and taper-shaped protrusions are accounted for 50-99.5%, 0.5-30% and 0-20% of the total number of protrusions, respectively. The density of the protrusions on the outside surface of the cylinder liner is 15-65 per square centimeter. The outer surface of the protrusions of the cylinder liner is curved, and has a large contact area and a concave which can be filled by an aluminum sheath to improve the radial bearing capacity, so as to effectively improve the bite force between the cylinder liner and the outside aluminum sheath and prevent the cylinder liner from breaking away from the cylinder body.